Psoriasis is a common skin condition affecting up to 1/50 people, and it affects men and women equally. It expresses variably among patients, but the most common type, plaque psoriasis, consists of raised lesions covered with a variable amount of silvery scales most commonly seen on the elbows, knees, scalp, and trunk. Other types of psoriasis are (linked) guttate, inverse, pustular, scalp, erythrodermic, and psoriatic inflammatory arthritis.
Some patients will develop only scalp involvement and this type of psoriasis can often be misdiagnosed as seborrhea (cradle cap) or tinea (fungal/ringworm). Generally there is a family history of psoriasis that can help with the diagnosis, and the scale of scalp psoriasis is usually more white/silvery than the waxy, off-white of seborrhea.
Because psoriasis is a systemic inflammatory condition, some patients may develop psoriatic arthritis, with or without skin lesions. There is usually asymmetrical joint pain, and it may affect only a few joints.
Psoriasis is often considered a skin condition, but in fact is a systemic disease resulting from a malfunction of the immune system, more specifically, overactive T-cells, a type of white blood cell involved in inflammatory activities. These overactive T-cells trigger other immune responses that cause increased blood flow and inflammation in the areas of involvement with resultant increases in skin growth. The increased growth of skin cells cannot be lost in a timely manner and an increased thickness (a plaque) of skin develops. This cycle repeats itself, causing scaling and plaques develop.
Psoriasis is very controllable, but not curable. Many things can trigger the onset and continuation of psoriasis:
- Bacterial and viral infections
- Stress: emotional or frictional on the skin surface inducing new areas of psoriasis and aggravating existing plaques
- Medications: beta-blockers, lithium, antimalarial medications, prednisone and other oral steroids
- Injury to the skin: intentional such as with surgery, or unintentional such as a cut or scrape
- Dry skin: may lead to scratching of the skin
- Too little sunlight and even too much sunlight causing a sunburn
- Nicotine: smoking and smokeless tobacco products
Patients with weakened immune systems (AIDS, chemotherapy patients, and patients with autoimmune disease such as rheumatoid arthritis) may have more severe bouts of psoriasis.
Treatment of psoriasis depends on the severity of involvement and what treatments have been employed in the past. The goal of therapy is to control the symptoms as well as to prevent secondary infections due to the disruption of the normal skin barrier functions.
Three basic therapeutic options exist for the treatment of psoriasis: topical, systemic, and phototherapy. Topical treatments include moisturisers, topical steroids, non-steroid topical treatments, "peeling" agents such as salicylic acids or lactic acids, and dandruff shampoos.
Moisturization of the skin alone may help a percentage of patients without the addition of anything else. Thicker, emollient creams are much more effective as moisturisers than lotion and in fact, some lotions, because of their water to oil ratio, may actually increase dryness of the skin.
Topical treatments include topical steroids in various formulations and strengths. The choice of formulation and strength is best determined with input from your dermatologist based on what has or has not worked in the past and what body site is being treated.
Coal tar products (OTC and Rx) have been used for years to help with psoriasis. They can be used in the bath as a soak or direct applied to the skin and left on for a variable amount of time. Other topical treatments include:
Salicylic and lactic acid, which are used to reduce the thickness of scales often in combination with moisturisers/steroids, Vitamin-D analog containing ointments, and Tazarotene (a topical retinoid).
Systemic therapies include oral and injectable products. Methotrexate is one of the older oral products used for psoriasis. It works by inhibiting an enzyme involved in rapid cell growth. Methotrexate can be taken orally or by injection and patients using this medication need to be monitored regularly with blood work and possibly a liver biopsy, especially with accumulated doses over months/years of therapy. Avoidance of alcohol is required while on this medicine.
Acitretin is another oral medicine for the treatment of psoriasis. This medicine needs regular monitoring, too, both for blood counts, liver enzymes, and triglyceride and cholesterol levels.
Cyclosporine which works to slow the growth of skin cells by suppressing the immune system directly has been used for psoriasis treatment, but is limited to a maximum of 9-12 months. Regular monitoring of therapy is required.
The other form of treatment for psoriasis is phototherapy. It involves careful exposure of your skin to ultraviolet light. Both UVA and UVB therapies are used and both require monitoring and care when using. Phototherapy may be used alone or in combination with topical and/or oral therapies. UVA therapy as a stand-alone treatment is not effective for psoriasis, but combining it with oral (or bath-applied) psoralens which makes the skin more sensitive to UVA light, is used and commonly called PUVA treatment. This type of treatment is undertaken at your physician's office or a treatment center. UVB light therapy can be used at home with purchased UVB light 'box' and monitored with regular interaction with your dermatologist or administered at your dermatologist's office.
Potential complications from psoriasis include arthritis, pain, itchiness which can sometimes be severe and may lead to secondary skin infections, side effects from your treatment medicines, psychiatric or depression episodes because of your condition and even skin cancer from UV treatments. All of these can be discussed, and very often controlled, with ongoing evaluations and discussions with your dermatologist.